660 lines
17 KiB
ArmAsm
660 lines
17 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Itanium 2-optimized version of memcpy and copy_user function
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*
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* Inputs:
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* in0: destination address
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* in1: source address
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* in2: number of bytes to copy
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* Output:
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* for memcpy: return dest
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* for copy_user: return 0 if success,
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* or number of byte NOT copied if error occurred.
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*
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* Copyright (C) 2002 Intel Corp.
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* Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
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*/
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#include <asm/asmmacro.h>
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#include <asm/page.h>
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#include <asm/export.h>
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#define EK(y...) EX(y)
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/* McKinley specific optimization */
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#define retval r8
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#define saved_pfs r31
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#define saved_lc r10
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#define saved_pr r11
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#define saved_in0 r14
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#define saved_in1 r15
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#define saved_in2 r16
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#define src0 r2
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#define src1 r3
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#define dst0 r17
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#define dst1 r18
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#define cnt r9
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/* r19-r30 are temp for each code section */
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#define PREFETCH_DIST 8
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#define src_pre_mem r19
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#define dst_pre_mem r20
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#define src_pre_l2 r21
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#define dst_pre_l2 r22
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#define t1 r23
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#define t2 r24
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#define t3 r25
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#define t4 r26
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#define t5 t1 // alias!
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#define t6 t2 // alias!
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#define t7 t3 // alias!
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#define n8 r27
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#define t9 t5 // alias!
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#define t10 t4 // alias!
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#define t11 t7 // alias!
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#define t12 t6 // alias!
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#define t14 t10 // alias!
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#define t13 r28
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#define t15 r29
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#define tmp r30
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/* defines for long_copy block */
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#define A 0
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#define B (PREFETCH_DIST)
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#define C (B + PREFETCH_DIST)
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#define D (C + 1)
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#define N (D + 1)
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#define Nrot ((N + 7) & ~7)
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/* alias */
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#define in0 r32
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#define in1 r33
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#define in2 r34
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GLOBAL_ENTRY(memcpy)
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and r28=0x7,in0
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and r29=0x7,in1
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mov f6=f0
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mov retval=in0
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br.cond.sptk .common_code
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;;
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END(memcpy)
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EXPORT_SYMBOL(memcpy)
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GLOBAL_ENTRY(__copy_user)
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.prologue
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// check dest alignment
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and r28=0x7,in0
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and r29=0x7,in1
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mov f6=f1
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mov saved_in0=in0 // save dest pointer
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mov saved_in1=in1 // save src pointer
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mov retval=r0 // initialize return value
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;;
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.common_code:
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cmp.gt p15,p0=8,in2 // check for small size
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cmp.ne p13,p0=0,r28 // check dest alignment
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cmp.ne p14,p0=0,r29 // check src alignment
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add src0=0,in1
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sub r30=8,r28 // for .align_dest
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mov saved_in2=in2 // save len
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;;
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add dst0=0,in0
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add dst1=1,in0 // dest odd index
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cmp.le p6,p0 = 1,r30 // for .align_dest
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(p15) br.cond.dpnt .memcpy_short
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(p13) br.cond.dpnt .align_dest
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(p14) br.cond.dpnt .unaligned_src
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;;
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// both dest and src are aligned on 8-byte boundary
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.aligned_src:
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.save ar.pfs, saved_pfs
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alloc saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
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.save pr, saved_pr
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mov saved_pr=pr
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shr.u cnt=in2,7 // this much cache line
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;;
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cmp.lt p6,p0=2*PREFETCH_DIST,cnt
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cmp.lt p7,p8=1,cnt
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.save ar.lc, saved_lc
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mov saved_lc=ar.lc
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.body
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add cnt=-1,cnt
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add src_pre_mem=0,in1 // prefetch src pointer
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add dst_pre_mem=0,in0 // prefetch dest pointer
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;;
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(p7) mov ar.lc=cnt // prefetch count
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(p8) mov ar.lc=r0
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(p6) br.cond.dpnt .long_copy
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;;
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.prefetch:
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lfetch.fault [src_pre_mem], 128
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lfetch.fault.excl [dst_pre_mem], 128
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br.cloop.dptk.few .prefetch
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;;
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.medium_copy:
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and tmp=31,in2 // copy length after iteration
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shr.u r29=in2,5 // number of 32-byte iteration
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add dst1=8,dst0 // 2nd dest pointer
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;;
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add cnt=-1,r29 // ctop iteration adjustment
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cmp.eq p10,p0=r29,r0 // do we really need to loop?
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add src1=8,src0 // 2nd src pointer
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cmp.le p6,p0=8,tmp
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;;
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cmp.le p7,p0=16,tmp
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mov ar.lc=cnt // loop setup
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cmp.eq p16,p17 = r0,r0
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mov ar.ec=2
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(p10) br.dpnt.few .aligned_src_tail
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;;
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TEXT_ALIGN(32)
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1:
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EX(.ex_handler, (p16) ld8 r34=[src0],16)
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EK(.ex_handler, (p16) ld8 r38=[src1],16)
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EX(.ex_handler, (p17) st8 [dst0]=r33,16)
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EK(.ex_handler, (p17) st8 [dst1]=r37,16)
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;;
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EX(.ex_handler, (p16) ld8 r32=[src0],16)
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EK(.ex_handler, (p16) ld8 r36=[src1],16)
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EX(.ex_handler, (p16) st8 [dst0]=r34,16)
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EK(.ex_handler, (p16) st8 [dst1]=r38,16)
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br.ctop.dptk.few 1b
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;;
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.aligned_src_tail:
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EX(.ex_handler, (p6) ld8 t1=[src0])
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mov ar.lc=saved_lc
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mov ar.pfs=saved_pfs
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EX(.ex_hndlr_s, (p7) ld8 t2=[src1],8)
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cmp.le p8,p0=24,tmp
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and r21=-8,tmp
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;;
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EX(.ex_hndlr_s, (p8) ld8 t3=[src1])
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EX(.ex_handler, (p6) st8 [dst0]=t1) // store byte 1
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and in2=7,tmp // remaining length
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EX(.ex_hndlr_d, (p7) st8 [dst1]=t2,8) // store byte 2
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add src0=src0,r21 // setting up src pointer
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add dst0=dst0,r21 // setting up dest pointer
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;;
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EX(.ex_handler, (p8) st8 [dst1]=t3) // store byte 3
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mov pr=saved_pr,-1
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br.dptk.many .memcpy_short
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;;
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/* code taken from copy_page_mck */
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.long_copy:
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.rotr v[2*PREFETCH_DIST]
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.rotp p[N]
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mov src_pre_mem = src0
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mov pr.rot = 0x10000
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mov ar.ec = 1 // special unrolled loop
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mov dst_pre_mem = dst0
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add src_pre_l2 = 8*8, src0
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add dst_pre_l2 = 8*8, dst0
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;;
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add src0 = 8, src_pre_mem // first t1 src
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mov ar.lc = 2*PREFETCH_DIST - 1
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shr.u cnt=in2,7 // number of lines
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add src1 = 3*8, src_pre_mem // first t3 src
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add dst0 = 8, dst_pre_mem // first t1 dst
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add dst1 = 3*8, dst_pre_mem // first t3 dst
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;;
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and tmp=127,in2 // remaining bytes after this block
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add cnt = -(2*PREFETCH_DIST) - 1, cnt
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// same as .line_copy loop, but with all predicated-off instructions removed:
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.prefetch_loop:
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EX(.ex_hndlr_lcpy_1, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0
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EK(.ex_hndlr_lcpy_1, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2
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br.ctop.sptk .prefetch_loop
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;;
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cmp.eq p16, p0 = r0, r0 // reset p16 to 1
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mov ar.lc = cnt
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mov ar.ec = N // # of stages in pipeline
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;;
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.line_copy:
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EX(.ex_handler, (p[D]) ld8 t2 = [src0], 3*8) // M0
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EK(.ex_handler, (p[D]) ld8 t4 = [src1], 3*8) // M1
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EX(.ex_handler_lcpy, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 prefetch dst from memory
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EK(.ex_handler_lcpy, (p[D]) st8 [dst_pre_l2] = n8, 128) // M3 prefetch dst from L2
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;;
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EX(.ex_handler_lcpy, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 prefetch src from memory
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EK(.ex_handler_lcpy, (p[C]) ld8 n8 = [src_pre_l2], 128) // M1 prefetch src from L2
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EX(.ex_handler, (p[D]) st8 [dst0] = t1, 8) // M2
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EK(.ex_handler, (p[D]) st8 [dst1] = t3, 8) // M3
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;;
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EX(.ex_handler, (p[D]) ld8 t5 = [src0], 8)
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EK(.ex_handler, (p[D]) ld8 t7 = [src1], 3*8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t2, 3*8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t4, 3*8)
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;;
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EX(.ex_handler, (p[D]) ld8 t6 = [src0], 3*8)
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EK(.ex_handler, (p[D]) ld8 t10 = [src1], 8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t5, 8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t7, 3*8)
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;;
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EX(.ex_handler, (p[D]) ld8 t9 = [src0], 3*8)
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EK(.ex_handler, (p[D]) ld8 t11 = [src1], 3*8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t6, 3*8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t10, 8)
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;;
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EX(.ex_handler, (p[D]) ld8 t12 = [src0], 8)
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EK(.ex_handler, (p[D]) ld8 t14 = [src1], 8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t9, 3*8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t11, 3*8)
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;;
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EX(.ex_handler, (p[D]) ld8 t13 = [src0], 4*8)
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EK(.ex_handler, (p[D]) ld8 t15 = [src1], 4*8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t12, 8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t14, 8)
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;;
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EX(.ex_handler, (p[C]) ld8 t1 = [src0], 8)
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EK(.ex_handler, (p[C]) ld8 t3 = [src1], 8)
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EX(.ex_handler, (p[D]) st8 [dst0] = t13, 4*8)
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EK(.ex_handler, (p[D]) st8 [dst1] = t15, 4*8)
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br.ctop.sptk .line_copy
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;;
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add dst0=-8,dst0
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add src0=-8,src0
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mov in2=tmp
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.restore sp
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br.sptk.many .medium_copy
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;;
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#define BLOCK_SIZE 128*32
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#define blocksize r23
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#define curlen r24
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// dest is on 8-byte boundary, src is not. We need to do
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// ld8-ld8, shrp, then st8. Max 8 byte copy per cycle.
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.unaligned_src:
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.prologue
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.save ar.pfs, saved_pfs
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alloc saved_pfs=ar.pfs,3,5,0,8
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.save ar.lc, saved_lc
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mov saved_lc=ar.lc
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.save pr, saved_pr
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mov saved_pr=pr
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.body
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.4k_block:
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mov saved_in0=dst0 // need to save all input arguments
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mov saved_in2=in2
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mov blocksize=BLOCK_SIZE
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;;
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cmp.lt p6,p7=blocksize,in2
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mov saved_in1=src0
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;;
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(p6) mov in2=blocksize
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;;
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shr.u r21=in2,7 // this much cache line
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shr.u r22=in2,4 // number of 16-byte iteration
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and curlen=15,in2 // copy length after iteration
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and r30=7,src0 // source alignment
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;;
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cmp.lt p7,p8=1,r21
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add cnt=-1,r21
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;;
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add src_pre_mem=0,src0 // prefetch src pointer
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add dst_pre_mem=0,dst0 // prefetch dest pointer
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and src0=-8,src0 // 1st src pointer
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(p7) mov ar.lc = cnt
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(p8) mov ar.lc = r0
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;;
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TEXT_ALIGN(32)
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1: lfetch.fault [src_pre_mem], 128
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lfetch.fault.excl [dst_pre_mem], 128
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br.cloop.dptk.few 1b
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;;
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shladd dst1=r22,3,dst0 // 2nd dest pointer
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shladd src1=r22,3,src0 // 2nd src pointer
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cmp.eq p8,p9=r22,r0 // do we really need to loop?
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cmp.le p6,p7=8,curlen; // have at least 8 byte remaining?
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add cnt=-1,r22 // ctop iteration adjustment
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;;
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EX(.ex_handler, (p9) ld8 r33=[src0],8) // loop primer
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EK(.ex_handler, (p9) ld8 r37=[src1],8)
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(p8) br.dpnt.few .noloop
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;;
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// The jump address is calculated based on src alignment. The COPYU
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// macro below need to confine its size to power of two, so an entry
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// can be caulated using shl instead of an expensive multiply. The
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// size is then hard coded by the following #define to match the
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// actual size. This make it somewhat tedious when COPYU macro gets
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// changed and this need to be adjusted to match.
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#define LOOP_SIZE 6
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1:
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mov r29=ip // jmp_table thread
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mov ar.lc=cnt
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;;
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add r29=.jump_table - 1b - (.jmp1-.jump_table), r29
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shl r28=r30, LOOP_SIZE // jmp_table thread
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mov ar.ec=2 // loop setup
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;;
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add r29=r29,r28 // jmp_table thread
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cmp.eq p16,p17=r0,r0
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;;
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mov b6=r29 // jmp_table thread
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;;
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br.cond.sptk.few b6
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// for 8-15 byte case
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// We will skip the loop, but need to replicate the side effect
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// that the loop produces.
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.noloop:
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EX(.ex_handler, (p6) ld8 r37=[src1],8)
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add src0=8,src0
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(p6) shl r25=r30,3
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;;
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EX(.ex_handler, (p6) ld8 r27=[src1])
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(p6) shr.u r28=r37,r25
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(p6) sub r26=64,r25
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;;
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(p6) shl r27=r27,r26
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;;
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(p6) or r21=r28,r27
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.unaligned_src_tail:
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/* check if we have more than blocksize to copy, if so go back */
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cmp.gt p8,p0=saved_in2,blocksize
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;;
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(p8) add dst0=saved_in0,blocksize
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(p8) add src0=saved_in1,blocksize
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(p8) sub in2=saved_in2,blocksize
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(p8) br.dpnt .4k_block
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;;
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/* we have up to 15 byte to copy in the tail.
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* part of work is already done in the jump table code
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* we are at the following state.
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* src side:
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*
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* xxxxxx xx <----- r21 has xxxxxxxx already
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* -------- -------- --------
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* 0 8 16
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* ^
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* |
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* src1
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*
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* dst
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* -------- -------- --------
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* ^
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* |
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* dst1
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*/
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EX(.ex_handler, (p6) st8 [dst1]=r21,8) // more than 8 byte to copy
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(p6) add curlen=-8,curlen // update length
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mov ar.pfs=saved_pfs
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;;
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mov ar.lc=saved_lc
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mov pr=saved_pr,-1
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mov in2=curlen // remaining length
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mov dst0=dst1 // dest pointer
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add src0=src1,r30 // forward by src alignment
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;;
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// 7 byte or smaller.
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.memcpy_short:
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cmp.le p8,p9 = 1,in2
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cmp.le p10,p11 = 2,in2
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cmp.le p12,p13 = 3,in2
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cmp.le p14,p15 = 4,in2
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add src1=1,src0 // second src pointer
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add dst1=1,dst0 // second dest pointer
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;;
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EX(.ex_handler_short, (p8) ld1 t1=[src0],2)
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EK(.ex_handler_short, (p10) ld1 t2=[src1],2)
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(p9) br.ret.dpnt rp // 0 byte copy
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;;
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EX(.ex_handler_short, (p8) st1 [dst0]=t1,2)
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EK(.ex_handler_short, (p10) st1 [dst1]=t2,2)
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(p11) br.ret.dpnt rp // 1 byte copy
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EX(.ex_handler_short, (p12) ld1 t3=[src0],2)
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EK(.ex_handler_short, (p14) ld1 t4=[src1],2)
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(p13) br.ret.dpnt rp // 2 byte copy
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;;
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cmp.le p6,p7 = 5,in2
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cmp.le p8,p9 = 6,in2
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cmp.le p10,p11 = 7,in2
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EX(.ex_handler_short, (p12) st1 [dst0]=t3,2)
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EK(.ex_handler_short, (p14) st1 [dst1]=t4,2)
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(p15) br.ret.dpnt rp // 3 byte copy
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;;
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EX(.ex_handler_short, (p6) ld1 t5=[src0],2)
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EK(.ex_handler_short, (p8) ld1 t6=[src1],2)
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(p7) br.ret.dpnt rp // 4 byte copy
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;;
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EX(.ex_handler_short, (p6) st1 [dst0]=t5,2)
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EK(.ex_handler_short, (p8) st1 [dst1]=t6,2)
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(p9) br.ret.dptk rp // 5 byte copy
|
|
|
|
EX(.ex_handler_short, (p10) ld1 t7=[src0],2)
|
|
(p11) br.ret.dptk rp // 6 byte copy
|
|
;;
|
|
|
|
EX(.ex_handler_short, (p10) st1 [dst0]=t7,2)
|
|
br.ret.dptk rp // done all cases
|
|
|
|
|
|
/* Align dest to nearest 8-byte boundary. We know we have at
|
|
* least 7 bytes to copy, enough to crawl to 8-byte boundary.
|
|
* Actual number of byte to crawl depend on the dest alignment.
|
|
* 7 byte or less is taken care at .memcpy_short
|
|
|
|
* src0 - source even index
|
|
* src1 - source odd index
|
|
* dst0 - dest even index
|
|
* dst1 - dest odd index
|
|
* r30 - distance to 8-byte boundary
|
|
*/
|
|
|
|
.align_dest:
|
|
add src1=1,in1 // source odd index
|
|
cmp.le p7,p0 = 2,r30 // for .align_dest
|
|
cmp.le p8,p0 = 3,r30 // for .align_dest
|
|
EX(.ex_handler_short, (p6) ld1 t1=[src0],2)
|
|
cmp.le p9,p0 = 4,r30 // for .align_dest
|
|
cmp.le p10,p0 = 5,r30
|
|
;;
|
|
EX(.ex_handler_short, (p7) ld1 t2=[src1],2)
|
|
EK(.ex_handler_short, (p8) ld1 t3=[src0],2)
|
|
cmp.le p11,p0 = 6,r30
|
|
EX(.ex_handler_short, (p6) st1 [dst0] = t1,2)
|
|
cmp.le p12,p0 = 7,r30
|
|
;;
|
|
EX(.ex_handler_short, (p9) ld1 t4=[src1],2)
|
|
EK(.ex_handler_short, (p10) ld1 t5=[src0],2)
|
|
EX(.ex_handler_short, (p7) st1 [dst1] = t2,2)
|
|
EK(.ex_handler_short, (p8) st1 [dst0] = t3,2)
|
|
;;
|
|
EX(.ex_handler_short, (p11) ld1 t6=[src1],2)
|
|
EK(.ex_handler_short, (p12) ld1 t7=[src0],2)
|
|
cmp.eq p6,p7=r28,r29
|
|
EX(.ex_handler_short, (p9) st1 [dst1] = t4,2)
|
|
EK(.ex_handler_short, (p10) st1 [dst0] = t5,2)
|
|
sub in2=in2,r30
|
|
;;
|
|
EX(.ex_handler_short, (p11) st1 [dst1] = t6,2)
|
|
EK(.ex_handler_short, (p12) st1 [dst0] = t7)
|
|
add dst0=in0,r30 // setup arguments
|
|
add src0=in1,r30
|
|
(p6) br.cond.dptk .aligned_src
|
|
(p7) br.cond.dpnt .unaligned_src
|
|
;;
|
|
|
|
/* main loop body in jump table format */
|
|
#define COPYU(shift) \
|
|
1: \
|
|
EX(.ex_handler, (p16) ld8 r32=[src0],8); /* 1 */ \
|
|
EK(.ex_handler, (p16) ld8 r36=[src1],8); \
|
|
(p17) shrp r35=r33,r34,shift;; /* 1 */ \
|
|
EX(.ex_handler, (p6) ld8 r22=[src1]); /* common, prime for tail section */ \
|
|
nop.m 0; \
|
|
(p16) shrp r38=r36,r37,shift; \
|
|
EX(.ex_handler, (p17) st8 [dst0]=r35,8); /* 1 */ \
|
|
EK(.ex_handler, (p17) st8 [dst1]=r39,8); \
|
|
br.ctop.dptk.few 1b;; \
|
|
(p7) add src1=-8,src1; /* back out for <8 byte case */ \
|
|
shrp r21=r22,r38,shift; /* speculative work */ \
|
|
br.sptk.few .unaligned_src_tail /* branch out of jump table */ \
|
|
;;
|
|
TEXT_ALIGN(32)
|
|
.jump_table:
|
|
COPYU(8) // unaligned cases
|
|
.jmp1:
|
|
COPYU(16)
|
|
COPYU(24)
|
|
COPYU(32)
|
|
COPYU(40)
|
|
COPYU(48)
|
|
COPYU(56)
|
|
|
|
#undef A
|
|
#undef B
|
|
#undef C
|
|
#undef D
|
|
|
|
/*
|
|
* Due to lack of local tag support in gcc 2.x assembler, it is not clear which
|
|
* instruction failed in the bundle. The exception algorithm is that we
|
|
* first figure out the faulting address, then detect if there is any
|
|
* progress made on the copy, if so, redo the copy from last known copied
|
|
* location up to the faulting address (exclusive). In the copy_from_user
|
|
* case, remaining byte in kernel buffer will be zeroed.
|
|
*
|
|
* Take copy_from_user as an example, in the code there are multiple loads
|
|
* in a bundle and those multiple loads could span over two pages, the
|
|
* faulting address is calculated as page_round_down(max(src0, src1)).
|
|
* This is based on knowledge that if we can access one byte in a page, we
|
|
* can access any byte in that page.
|
|
*
|
|
* predicate used in the exception handler:
|
|
* p6-p7: direction
|
|
* p10-p11: src faulting addr calculation
|
|
* p12-p13: dst faulting addr calculation
|
|
*/
|
|
|
|
#define A r19
|
|
#define B r20
|
|
#define C r21
|
|
#define D r22
|
|
#define F r28
|
|
|
|
#define saved_retval loc0
|
|
#define saved_rtlink loc1
|
|
#define saved_pfs_stack loc2
|
|
|
|
.ex_hndlr_s:
|
|
add src0=8,src0
|
|
br.sptk .ex_handler
|
|
;;
|
|
.ex_hndlr_d:
|
|
add dst0=8,dst0
|
|
br.sptk .ex_handler
|
|
;;
|
|
.ex_hndlr_lcpy_1:
|
|
mov src1=src_pre_mem
|
|
mov dst1=dst_pre_mem
|
|
cmp.gtu p10,p11=src_pre_mem,saved_in1
|
|
cmp.gtu p12,p13=dst_pre_mem,saved_in0
|
|
;;
|
|
(p10) add src0=8,saved_in1
|
|
(p11) mov src0=saved_in1
|
|
(p12) add dst0=8,saved_in0
|
|
(p13) mov dst0=saved_in0
|
|
br.sptk .ex_handler
|
|
.ex_handler_lcpy:
|
|
// in line_copy block, the preload addresses should always ahead
|
|
// of the other two src/dst pointers. Furthermore, src1/dst1 should
|
|
// always ahead of src0/dst0.
|
|
mov src1=src_pre_mem
|
|
mov dst1=dst_pre_mem
|
|
.ex_handler:
|
|
mov pr=saved_pr,-1 // first restore pr, lc, and pfs
|
|
mov ar.lc=saved_lc
|
|
mov ar.pfs=saved_pfs
|
|
;;
|
|
.ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs
|
|
cmp.ltu p6,p7=saved_in0, saved_in1 // get the copy direction
|
|
cmp.ltu p10,p11=src0,src1
|
|
cmp.ltu p12,p13=dst0,dst1
|
|
fcmp.eq p8,p0=f6,f0 // is it memcpy?
|
|
mov tmp = dst0
|
|
;;
|
|
(p11) mov src1 = src0 // pick the larger of the two
|
|
(p13) mov dst0 = dst1 // make dst0 the smaller one
|
|
(p13) mov dst1 = tmp // and dst1 the larger one
|
|
;;
|
|
(p6) dep F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary
|
|
(p7) dep F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary
|
|
;;
|
|
(p6) cmp.le p14,p0=dst0,saved_in0 // no progress has been made on store
|
|
(p7) cmp.le p14,p0=src0,saved_in1 // no progress has been made on load
|
|
mov retval=saved_in2
|
|
(p8) ld1 tmp=[src1] // force an oops for memcpy call
|
|
(p8) st1 [dst1]=r0 // force an oops for memcpy call
|
|
(p14) br.ret.sptk.many rp
|
|
|
|
/*
|
|
* The remaining byte to copy is calculated as:
|
|
*
|
|
* A = (faulting_addr - orig_src) -> len to faulting ld address
|
|
* or
|
|
* (faulting_addr - orig_dst) -> len to faulting st address
|
|
* B = (cur_dst - orig_dst) -> len copied so far
|
|
* C = A - B -> len need to be copied
|
|
* D = orig_len - A -> len need to be left along
|
|
*/
|
|
(p6) sub A = F, saved_in0
|
|
(p7) sub A = F, saved_in1
|
|
clrrrb
|
|
;;
|
|
alloc saved_pfs_stack=ar.pfs,3,3,3,0
|
|
cmp.lt p8,p0=A,r0
|
|
sub B = dst0, saved_in0 // how many byte copied so far
|
|
;;
|
|
(p8) mov A = 0; // A shouldn't be negative, cap it
|
|
;;
|
|
sub C = A, B
|
|
sub D = saved_in2, A
|
|
;;
|
|
cmp.gt p8,p0=C,r0 // more than 1 byte?
|
|
mov r8=0
|
|
mov saved_retval = D
|
|
mov saved_rtlink = b0
|
|
|
|
add out0=saved_in0, B
|
|
add out1=saved_in1, B
|
|
mov out2=C
|
|
(p8) br.call.sptk.few b0=__copy_user // recursive call
|
|
;;
|
|
|
|
add saved_retval=saved_retval,r8 // above might return non-zero value
|
|
;;
|
|
|
|
mov retval=saved_retval
|
|
mov ar.pfs=saved_pfs_stack
|
|
mov b0=saved_rtlink
|
|
br.ret.sptk.many rp
|
|
|
|
/* end of McKinley specific optimization */
|
|
END(__copy_user)
|
|
EXPORT_SYMBOL(__copy_user)
|